1. Systematic Oblique Aerial Photography Using Multiple Digital Cameras by Prof. Gordon Petrie (Univ. of Glasgow ) VIII International Scientific & Technical Conference “ From Imagery to Map: Digital Photogrammetric Technologies” September 15-18, 2008 – Porec, Croatia

5. Oblique Photography (Manned) (a) Area of great activity in some countries – e.g. in U.K., more than 60 companies engaged in this field. (b) Oblique photos used extensively for visualization by estate agents & property developers; for monitoring progress on projects (for payments) by civil engineers and builders. (c) Oblique frame photos are commissioned specifically for a particular site or property or area on contract – not for stock. (d) Mostly Cessna 172 aircraft are used – widely available; very cheap to operate - £200 per hour. (e) Some limited use of helicopters , but very high cost to operate – £800 per hour.

7. Oblique Photography (Unmanned) (d) The use of tethered (unpowered) blimps is also very widespread – more than 10 companies operating in the U.K. (e) Most widespread of all is the use of telescopic masts – in U.K., 55 companies operate in this market. (f) Both film & digital frame cameras are used to acquire the required oblique aerial photography.

8. Oblique Photography (Unmanned) Use of digital cameras from unmanned platforms by the Skycell company.

9. Single Cameras – Multiple Obliques Stepping frame camera - A sequence of oblique photos is exposed cross-track at a very high speed to provide a very wide angular coverage of the ground. VisionMap (Israel) Twin cameras side-by-side in a cross-track scan.

12. Two Oblique Cameras (a) IGI (Germany) offers its Dual-DigiCAM system. (b) Comprises twin digital cameras (Hasselblad-based) with 39 Mpix digital backs. (c) One exposure = 2 photos. (d) Rectification & stitching. (e) Again wide cross-track coverage – 10k or 13k pixels. Final rectified & stitched image with wide cross-track coverage Flight diagram for three strips of dual oblique images

18. Four Camera Systems Again the arrangement of the Zeiss four-coupled oblique film cameras from the 1930s is being replicated in the new Rolleimetric AIC x4 digital camera system. Final rectified & stitched orthophoto Four separate (tilted) photos

21. Four Camera Systems Intergraph DMC (a) Each of the 4 medium-format oblique pan images is rectified and they are then stitched together using tie points in the overlap areas. (b) The final “ virtual image ” is then “ colourized ” using the data from the four small-format multi-spectral cameras

23. Five Camera Systems (a) During the 1930s, extensive use of the Fairchild T-3A 5-lens film camera systems in the U.S.A. (b) Each comprised one vertical & four oblique cameras in a single housing with 5 separate film magazines. (c) 30 T-3A systems were built. (d) Lens was f = 150mm ; each of the five photos was 13.5 x 15 cm in size (e) Produced a “ Maltese Cross ” coverage of the ground. (f) The photography was used extensively by USCE and USGS for mapping using both graphical radial triangulation and stereo-plotting instruments.

29. Five Camera System

30. Five Camera System (a) COWI (Denmark) operates two of the MIDAS five-camera systems for the acquisition of systematic oblique photography. (b) The company formerly used MultiVision ; now it uses its own software.

33. Five Camera System “Community” Ortho Image “Community” Oblique Image

34. Five Camera System “Neighbourhood” Oblique Image

35. Five Camera System Pictometry Applications (a) In the U.S.A., the biggest use of Pictometry imagery appears to be by homeland security (police) agencies & emergency (fire, ambulance) services. (b) Images are available on laptops or are sent by radio .

36. Five Camera System Pictometry images are much used also on the Microsoft Virtual Earth mapping & imaging platform

37. Five Camera System

39. Multi-Lens Film Cameras (a) The famous 8-lens camera of Schiempflug from 1904 used to take aerial photos from blimps. (b) The Barr & Stroud 7-lens camera designed by E.H. Thompson ; built in the 1930s.

40. Multi-Lens Film Cameras (a) Another well-known example is the 9-lens camera of Aschenbrenner from 1926 ; a later version was built for Photogrammetrie GmbH . (b) This camera was used to acquire the first aerial photography used for the mapping of the Russian Arctic islands from the Graf Zeppelin airship in 1931 .

41. Multi-Lens Film Cameras Another well-known 9-lens camera to a similar design by Reading of the U.S. Coast & Geodetic Survey (now part of NOAA) - that was built by Fairchild.

42. Six Camera System (a) Several six-coupled cameras have come into operation recently. (b) From the U.S.A. have come the ITT/Geospatial Systems “six-pack” with real-time transmission of the images (66 Mpix) to the ground station for persistent surveillance . (c) Follow-on “scaleable” systems with a much larger number of oblique cameras are being built that will produce 176 Mpix and 584 Mpix images respectively.